Manganese Nitride Complexes in Oxidation States III, IV, and V: Synthesis and Electronic Structure

The synthesis and characterization of a series of manganese nitrides in a tripodal chelating tris­(carbene) ligand framework is described. Photolysis of [(TIMENxyl)­Mn­(N3)]+ (where TIMENxyl = tris­[2-(3-xylylimidazol-2-ylidene)­ethyl]­amine) yields the isolable molecular MnIV nitride, [(TIMENxyl)­Mn­(N)]+. Spectroscopic and DFT studies indicate that this MnIV d3 complex has a doublet electronic ground state. The metal-centered one-electron oxidation of this MnIV species results in formation of the pentavalent MnV nitride, [(TIMENxyl)­Mn­(N)]2+. Unlike previously reported, tetragonal MnV nitrides with a d2, nonmagnetic S = 0 ground state, this trigonal bipyramidal complex has a triplet ground state S = 1. One-electron reduction of [(TIMENxyl)­Mn­(N)]+ produces the neutral, nonmagnetic trivalent [(TIMENxyl)­Mn­(N)] species with a d4 low-spin, S = 0, ground state.